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Analyzing Arabidopsis thaliana root proteome provides insights into the molecular bases of enantioselective imazethapyr toxicity.

Qian H, Lu H, Ding H, Lavoie M, Li Y, Liu W, Fu Z - Sci Rep (2015)

Bottom Line: Here, we exposed the model plant Arabidospsis thaliana to trace S- and R-IM enantiomer concentrations and examined IM toxicity effects on the root proteome using iTRAQ.Bioinformatics and physiological analyses suggested that IM reduced the BCAA tissue content not only by strongly suppressing BCAA synthesis but also by increasing BCAA catabolism.The present study shed new light on the multiple toxicity mechanisms of a selective herbicide on a model plant.

View Article: PubMed Central - PubMed

Affiliation: 1] Department of Food Science and Technology, Zhejiang University of Technology, Hangzhou 310032, P. R. of China [2] College of Biological and Environmental Engineering, Zhejiang University of Technology, Hangzhou 310032, P. R. of China.

ABSTRACT
Imazethapyr (IM) is a widely used chiral herbicide that inhibits the synthesis of branched-chain amino acids (BCAAs). IM is thought to exert its toxic effects on amino acid synthesis mainly through inhibition of acetolactate synthase activity, but little is known about the potential effects of IM on other key biochemical pathways. Here, we exposed the model plant Arabidospsis thaliana to trace S- and R-IM enantiomer concentrations and examined IM toxicity effects on the root proteome using iTRAQ. Conventional analyses of root carbohydrates, organic acids, and enzyme activities were also performed. We discovered several previously unknown key biochemical pathways targeted by IM in Arabidospsis. 1,322 and 987 proteins were differentially expressed in response to R- and S-IM treatments, respectively. Bioinformatics and physiological analyses suggested that IM reduced the BCAA tissue content not only by strongly suppressing BCAA synthesis but also by increasing BCAA catabolism. IM also affected sugar and starch metabolism, changed the composition of root cell walls, increased citrate production and exudation, and affected the microbial community structure of the rhizosphere. The present study shed new light on the multiple toxicity mechanisms of a selective herbicide on a model plant.

No MeSH data available.


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Conceptual scheme describing the toxic effects of IM in A. thaliana roots and the potential influence of organic acid secretion on the rhizosphere bacterial community.
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f6: Conceptual scheme describing the toxic effects of IM in A. thaliana roots and the potential influence of organic acid secretion on the rhizosphere bacterial community.

Mentions: Our results not only provide a comprehensive analysis of IM toxicity effects in A. thaliana, but also provide evidence that the toxic effect of IM on A. thaliana is related to changes in diversity and abundance of microorganisms in the rhizosphere (See Fig. 6 for a conceptual scheme summarizing the multiple IM toxic effects in A. thaliana). Roots are known to excrete secondary metabolites that act as messengers that attract Rhizobium and arbuscular mycorrhizal fungi38. More specifically, Rudrappa et al. demonstrated that the secretion of the TCA cycle intermediate L-malic acid from A. thaliana roots is used to recruit the beneficial rhizobacterium Bacillus subtilis39. Therefore, in the present study, the measured increase in citrate exudation from A. thaliana roots (Fig. 4D) in response to IM stress could explain the observed increase in B. subtilis abundance in the rhizopshere of IM-treated A. thaliana. Furthermore, the increase in Acidovorax, an acidophilic bacterium40, abundance in the rhizosphere (Fig. 3F) of IM-treated plants could also be related to exudation of organic acid from plant roots4142. Further studies are clearly needed to confirm/infirm the above hypothetical interactions between bacterial community structure of the rhizosphere and IM.


Analyzing Arabidopsis thaliana root proteome provides insights into the molecular bases of enantioselective imazethapyr toxicity.

Qian H, Lu H, Ding H, Lavoie M, Li Y, Liu W, Fu Z - Sci Rep (2015)

Conceptual scheme describing the toxic effects of IM in A. thaliana roots and the potential influence of organic acid secretion on the rhizosphere bacterial community.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4495388&req=5

f6: Conceptual scheme describing the toxic effects of IM in A. thaliana roots and the potential influence of organic acid secretion on the rhizosphere bacterial community.
Mentions: Our results not only provide a comprehensive analysis of IM toxicity effects in A. thaliana, but also provide evidence that the toxic effect of IM on A. thaliana is related to changes in diversity and abundance of microorganisms in the rhizosphere (See Fig. 6 for a conceptual scheme summarizing the multiple IM toxic effects in A. thaliana). Roots are known to excrete secondary metabolites that act as messengers that attract Rhizobium and arbuscular mycorrhizal fungi38. More specifically, Rudrappa et al. demonstrated that the secretion of the TCA cycle intermediate L-malic acid from A. thaliana roots is used to recruit the beneficial rhizobacterium Bacillus subtilis39. Therefore, in the present study, the measured increase in citrate exudation from A. thaliana roots (Fig. 4D) in response to IM stress could explain the observed increase in B. subtilis abundance in the rhizopshere of IM-treated A. thaliana. Furthermore, the increase in Acidovorax, an acidophilic bacterium40, abundance in the rhizosphere (Fig. 3F) of IM-treated plants could also be related to exudation of organic acid from plant roots4142. Further studies are clearly needed to confirm/infirm the above hypothetical interactions between bacterial community structure of the rhizosphere and IM.

Bottom Line: Here, we exposed the model plant Arabidospsis thaliana to trace S- and R-IM enantiomer concentrations and examined IM toxicity effects on the root proteome using iTRAQ.Bioinformatics and physiological analyses suggested that IM reduced the BCAA tissue content not only by strongly suppressing BCAA synthesis but also by increasing BCAA catabolism.The present study shed new light on the multiple toxicity mechanisms of a selective herbicide on a model plant.

View Article: PubMed Central - PubMed

Affiliation: 1] Department of Food Science and Technology, Zhejiang University of Technology, Hangzhou 310032, P. R. of China [2] College of Biological and Environmental Engineering, Zhejiang University of Technology, Hangzhou 310032, P. R. of China.

ABSTRACT
Imazethapyr (IM) is a widely used chiral herbicide that inhibits the synthesis of branched-chain amino acids (BCAAs). IM is thought to exert its toxic effects on amino acid synthesis mainly through inhibition of acetolactate synthase activity, but little is known about the potential effects of IM on other key biochemical pathways. Here, we exposed the model plant Arabidospsis thaliana to trace S- and R-IM enantiomer concentrations and examined IM toxicity effects on the root proteome using iTRAQ. Conventional analyses of root carbohydrates, organic acids, and enzyme activities were also performed. We discovered several previously unknown key biochemical pathways targeted by IM in Arabidospsis. 1,322 and 987 proteins were differentially expressed in response to R- and S-IM treatments, respectively. Bioinformatics and physiological analyses suggested that IM reduced the BCAA tissue content not only by strongly suppressing BCAA synthesis but also by increasing BCAA catabolism. IM also affected sugar and starch metabolism, changed the composition of root cell walls, increased citrate production and exudation, and affected the microbial community structure of the rhizosphere. The present study shed new light on the multiple toxicity mechanisms of a selective herbicide on a model plant.

No MeSH data available.


Related in: MedlinePlus